Fitting transponder

[Yenn]

Can anyone advise me what is required to fit a transponder?

 

Does it need an encoding altimeter or can it work without, type of aerial etc?

 

 

[icebob]

Hi Yenn,

 

I got the microair kit, has the lot with it. The only thing I did different was fit a disc of 6061T6 for the aerial as the pod skin was a little flexable and it would act as a ground plane too.

 

The wiring kit included was easy to rig up the only fiddly bit was securing the encoder.

 

Bob.

 

 

[facthunter]

More.

 

They have their own baro in most installatons, which is required to be calibrated every two years. I really know very little else except that they may need to be shielded from you and the need for a special aerial in non metal aircraft.

 

 

[jetjr]

If you have a Dynon screen etc you can use the alt info from here but its not TSO (but meets the std)

 

Many use this for Txr, saves the cost and weight of separate encoder

 

Im a bit lost by the 2 diagrams for wiring these 2 together, has adapter gizmo in one and direct serial connection in another? Anyone understand this?

 

 

[Guest Andys@coffs]

Yenn

 

The encoding altimeter is required if you intend your transponder to work in mode 3C. If it is 3A that is all you intend tyhen no. That said, everywhere that CASA calls for a transpondef to be fitted and serviceable it is as a 3C transponder.

 

If you are looking to purchase one, make sure that it will work without issue with the new Mode S SSR radar heads that we now have in Australia. Some of the earlier Microair transponders have glitches where they loose encoded altitude and effectively default back to 3A behaviour. WHile MIcroair will upgrade existing ones I believe that it has some significant hip pocket pain associated with that upgrade.

 

The encode plumbs into the same static air pressure source as your normal altimeter and as Nev suggests there is a requirement for a calibrated "suck and blow" machine to be used biannually by a licensed avionics LAME to assure that the encoder is accurate.

 

Unless you need to enter Controlled airspace, or are seriously concerned about being rear ended by something much faster than you Im of the view that its all to hard. My aircraft has one fitted, but its an early model microair and its out of date for cal. As a result I dont turn it on, or just use 3A. Im not sure that 3A will help with TCAS fitted aircraft. I suspect that altitude info is used in conjunction with time of interogation and time of response to determine how much of an issue a close transponder equiped aircraft is. Perhaps someone who is an avionics LAME and or has an ATP can comment?

 

Andy

 

 

[kaz3g]

Microair ID didn't work

 

Hi All

 

I went up the inland route yesterday from Sugarloaf to Wandong in some serious haze. As I passed over the top of Sugarloaf at 2500, an Airtourer passed diagonally beneath me from behind at around 2000'.

 

I called MLRADAR and let them know (a) that I was heading north along the corridor and (b) someone was fairly close to me. When asked to sqawk ident I pushed the ID button but nothing happened. I was in mode C at the time and on 1200. He had me on radar and my altitude but I didn't light up his display.

 

Any ideas, pls?

 

kaz

 

 

[Yenn]

Thanks all of you for the info. I will be building an RV4 which will be GA registered, unless RAA weight limits are lifted. I had this question of the SAAA website for over a week and not one answer. This is the top place for info exchange in Australia.

 

 

[Guest Qwerty]

Yenn, I recently did this. Buy a Microair transponder kit for about $3,000, then you put it in. Its dead easy, it really is childs play. The only thing not supplied in the kit is a ground plane but the RV IS a ground plane.

 

Cheers, Qwerty

 

 

[Alpi]

Hi AllI went up the inland route yesterday from Sugarloaf to Wandong in some serious haze. As I passed over the top of Sugarloaf at 2500, an Airtourer passed diagonally beneath me from behind at around 2000'.

 

I called MLRADAR and let them know (a) that I was heading north along the corridor and (b) someone was fairly close to me. When asked to sqawk ident I pushed the ID button but nothing happened. I was in mode C at the time and on 1200. He had me on radar and my altitude but I didn't light up his display.

 

Any ideas, pls?

 

kaz

Hi Kaz

Try pressing Enter then ID, as per T2000 usermanual V2.9.

 

User manual V2.7 simply says press ID,as you've discovered this does not work.

 

Regards

 

Greg

 

 

[kaz3g]

Thank you, Greg.

 

I read and re-read the manual after this and still couldn't figure what I was doing wrong.

 

I've knocked up about 75 hours in BYM since I purchased it 12 months back but have never had to use the ident before. I plan on going down to Point Cook for the Air Pageant on 28 Feb so will definitely need it then.

 

As soon as I get a chance to try it, I'll fire it up in the hangar on the ground where it won't cause troubles with ATC.

 

Have a great 2010

 

kaz

 

 

[Thalass]

I don't have the books in front of me at the moment, but if I recall correctly (and I could well be wrong here, so use a good helping of salt with this) mode C only gives altitude encoding, so an aircraft with a tcas system will get a position and altitude on their display, but the two aircraft cannot talk to one another, so their system will tell them to avoid you like the plague. Whereas a mode S transponder can chat between each other, and decide who is to go up, and who is to go down. So the pilot (or most likely the autopilot) will be given a command that doesn't conflict with the other aircraft. I believe the tower will also get additional information (rego, flight number, perhaps, and other stuff extracted from the flight plan database, with a mode-s transponder, as each one has a unique number registered to the aircraft it is installed in.

 

But I'm a bit rusty, so I might be wrong. :P

 

 

[Guest Andys@coffs]

Actually I went and googled TCAS and found the following extract from an old (2000) casa FSA publication:-

 

For all its benefits TCAS has one major weakness – it “sees” transponders, not aircraft. That means that aircraft not fitted with transponders are invisible to TCAS. Similarly if you have a transponder and don’t turn it on, or you have the wrong type of transponder, the system won’t be able to help you. (TCAS can only “see”Mode-A/C and Mode-S transponders not Mode-Aonly units.) The capabilities of TCAS are also significantly limited if a transponder is turned on but the the ALT function (mode C) is ot selected. This is because TCAS separates aircraft vertically – if a transponder is not transmitting altitude information the ystem cannot provide separation instructions.

 

 

 

 

 

 

 

That extract backs my earlier asertion that Mode A might not be of use with TCAS. Full article here http://www.casa.gov.au/wcmswr/_assets/main/fsa/2000/jan/page31.pdf

 

 

 

 

 

 

 

Andy

 

 

 

 

 

 

[Thalass]

Andys: This is why you need a transponder to fly in controlled airspace, and up around the higher altitudes where more (and larger) aircraft roam. Even if you're only mode-c, they'd be able to see you and avoid you.

 

Of course I understand the cost involved, but thats the price you would have to pay to fly in controlled airspace. Though it occurs to me that perhaps a mode-c transponder (ie: without the mode-s 24bit unique code linked to your airframe) could be club-owned, and borrowed or rented on the odd occasion you want to fly through controlled airspace. That way the purchase and maintenance costs would be split among members of that club. Not sure if that's practical or legal, though. I don't think you can get portable ATC systems, and if you share a rack-mounted jobbie, then you still have to route the wires and such so you might as well have your own at that point. But it would ease that particular issue I think.

 

*edit*

 

Thinking about it more, I seriously doubt there's any such thing as a handheld atc. They put out quite a bit of power and they are almost constantly transmitting. Gives you a headache even when you're six or seven metres away from the antenna - I know this from experience.

 

However it may be possible to do a temporary install with a set length of cable and an atc box that has its own altitude sensor built in - so you'd only have to supply power and route the cable to the antenna, which I suppose could be duct-taped to the side of the fuselage or something like that. Dodgy, I know, but possibly doable. I don't know the ins and outs of modifying an RA aircraft. At work (group 20 commercial aircraft) you do nothing without an EO or SB or some kind of legal XXXX-covering stuff from the manufacturer or design department or something like that. As long as it was a secure temporary installation, it ought to be ok, I imagine. And if it was a self-contained atc box its calibration wouldn't be tied to any one aircraft.